……..I’m missing something and I can’t think what.
Had a neighbours bike in today. The gears went up the block nicely but didn’t come down smoothly.
I changed the rear inner and outer as that normally cures it but it didn’t this time. Made it better but clunky on the downshift still.
The chain is worn beyond .75 but not as far as 1 on my chain checker. I tried a new chain and it made a slight difference but not much.
The cassette is original but looks good (no obvious worn cogs) It’s on good and tight with no play. It didn’t skip with a new chain so that’s good in my book.
The mech alignment looks good and the bike hasn’t suffered any obvious frame damage.
Before I try replacing the mech as the spring might be baggy is there anything else to check?
Cheers
Tim

Check teh little adjuster screw that pulls the top jockey away from the casette.

Does the mech move freely without a cable/chain?

Maybe try lubing the shifter

mech pivots?

Jockey wheels well spaced.
Shifter smooth
Mech smooth in movement
Will check the pivots but I’ve had the wheel in and out a couple of times and it appeared to be working as it should.

demonic possession?

Is the mech loose in the hanger or is the hanger loose?

demonic possession?

Kink in the front outer cable?

Mech spring if its relying on that.

mech alignment looks good

Are you eye-balling it or using a alignment tool? Hanger can look straight but be off enough to effect shifting in just the way you describe, shifts well in one direction and terrible in the other.

Sorry to patronise f you have checked this but the number of time I’ve had people say hang looks straight and that being the problem is,… well enough for me to double check what they mean.

Bent mech hanger ?

Bad cable outer routing?

Hanger slightly twisted rather than bent…?

make sure the outer isnt TOO long ie. no tighter than necessary bends etc.

Also make sure the cable is routed correctly on the mech itself.

“Bent mech hanger ? “

Yup. Tips on how to check this reliably would be a good PSA, again.

It sounds like cable stick, but you’ve changed the rear inner and outer – maybe it’s sticking at the front? If you slack the lever right off, and move the mech up by pulling the free section of inner, how does it go back down?

its got gears. take them off, leave the shifter on and tell no one.

don’t forget to tell the neighbour he looks fat and is out of shape.

Radius of cable entry to mech too tight??

Check the main overhead underhang,to see if the thrust washers ok !. 😉

Had a neighbours bike in today.

This makes me think you’re a mechanic.

The chain is worn beyond .75 but not as far as 1 on my chain checker.

This make me hope you aren’t!

Chain checkers (unless it’s the £50 Shimano one, measure roller wear, which is completely irrelevant. Use a bloody rule!

Replace chain when 12 link pairs measure 12.0625” (12 1/16”) or 0.5% (as recommended by the late great Sheldon Brown & Jobst Brandt).